Cellular communication devices such as cellular telephones, tablets, and laptops can support multi-cellular access technologies, peer-to-peer access technologies, personal area network access technologies, and location receiver access technologies, which can operate concurrently. Cellular communication devices have also integrated a variety of consumer features such as MP3 players, color displays, gaming applications, cameras, and other features. Cellular communication devices can be required to communicate at a variety of frequencies, and in some instances are subjected to a variety of physical and functional use conditions.
In some instances, such communication devices are required to operate within different frequency bands, referred to generally as multi-band operation. For example, a cellular communication device may be required to operate in a low-frequency cellular band, e.g., for voice communications, and in a relatively high-frequency cellular band, e.g., for data communications. Additionally, with advancements in mobile communications devices resulting in smaller packages with greater functionality, such a demand for multi-band operation without a corresponding proliferation of antennas is desirable.
Multiband antennas can provide coverage within different operating bands, such as a planar inverted “F” antenna (PIFA) used in mobile communications devices. Unfortunately, however, such antennas typically provide relatively narrow operational bandwidths determined by resonances of the multiband antenna structures. Thus, if greater bandwidth coverage is required, additional elements area may be added, adding to the size and complexity of the multiband antenna structure.